Marine preserves based on faulty analysis
By John S. Calvo • August 12, 2009
The Bill 190 opponents state that the Marine Protected Areas have been successful. The only thing successful has been their propaganda.
In the absence of a thorough review of important maps, a field trip around the island shows various obstacles (accessibility, natural boundaries, military bases, private property) inadvertently but effectively create marine preserves. If we already have natural, political and social marine preserves that take up 50 to 75 percent of our coastal areas, then what is the need for additional preserves?
The creation of Guam's marine preserves in Public Law 24-21 primarily focused on regulating only one user group -- the fishing community. The proponents of the MPAs will state that they used the best available science. According to the Marine Preserve two-year report to the Legislature in July 5, 2005, "Harvest and participation data obtained through the Inshore Fisheries Survey Project (F-1R, Subproject F-1, Study 1, Job 2) were used to justify the establishment of the marine preserves."
There are some major failures of the survey analysis. Why were only so many fish caught? Why were the conditions of harvest not part of the survey? Why were the variables such as water quality, runoff, etc., not also studied to rule these factors out in the determination that fish stocks were down due to overfishing? Why wasn't the habitat studied to rule out the health of the habitat as the reason for a reduction in fish stocks?
Science is a process of deduction. The best available science existed at the time to do these things; why it wasn't done or considered is baffling.
Wolanski and Richmond's 2004 study on Fouha Bay notes, "Until recently, the major strategy for coastal reef management is to rely on marine protected areas. Managers draw a line around coral reefs on a map, inside of which extractive and destructive activities are prohibited or regulated. ... This management practice has proven insufficient where coral reefs are found near land and where human activities within adjacent watersheds contribute to the decline of water and substratum quality."
This study indicates that even if fishing is eliminated, an area will continue to decline if other threats are left unabated. It also indicates a failure of government of Guam agencies to work together to solve the island's land use problems. Why must the fishing community suffer for the effects of land use practices and poor natural resource agency management?
Division of Aquaric and Wildlife Resources staff has frequently noted at public meetings that the marine preserve areas provide a "spillover" effect, where fish stocks within the preserve area will continue to reproduce and essentially fill up the preserve, causing fish to "spill over" into adjoining areas. Another version of the theory is that protecting fish stocks within an area will allow those fish to reproduce and the larvae would be transported out of the area and settle in adjoining areas.
Marine preserve areas do not work for all species. Ken Longenecker and Ross Langston presented at the 2007 Hawaii Conservation Conference on the biomass of three fish species in Haunama Bay and Maunalua Bay in Hawaii. Their findings suggest that in order for MPAs to be a beneficial tool for fisheries enhancement, biomass in the closed area must be at least double the open area. In their study, they found this is not happening in Hawaii's most famous and oldest no-fishing area. Their study suggests that MPAs are not a beneficial tool for fisheries management for the species that were studied.
Mark Tupper of the University of Guam Marine Laboratory studied the "Spillover of commercially valuable reef fishes from marine protected areas in Guam, Micronesia." He notes that "for most species and sites, biomass was significantly higher within the MPA's than in adjacent fished sites. Movement of fishes into and out of the MPAs were determined by mark-recapture experiments, in which fishes were tagged both inside and outside of MPAs. Four out of five species studied showed little or no net movement out of the MPAs."
This study demonstrates that MPAs can enhance export of fish biomass to fished areas, but spillover is species-specific and depends on factors such as species size and mobility. The study notes: "For the combination of all species, overall spillover was lowest at the Tumon MPA, where only 1.7 percent of all tagged biomass was exported."
Another problem with the "spillover" theory is that it can't be assumed to work in any area that becomes protected. Spillover may work for certain species, but only if the boundaries and locations are chosen correctly.
The study by Tupper mentioned previously also noted that "Patterns of spillover were strongly influenced by physical habitat barriers, such as channels, headlands, or other topographic features. MPAs that are physically connected by contiguous reef structures will likely provide more spillover to adjacent fished sites than those that are separated by habitat barriers."
Tupper's conclusion states: "Knowledge of fish movement patterns with respect to reef topography may be useful for choosing MPA boundaries in order to maximize spillover of target species."
In determining the location of any marine protected area, it is also beneficial to consider those areas that already are least accessible due to the natural, political and other obstacles. For centuries these have provided for natural spillover, which have made the cultural and traditional fishing areas productive. Mitigation of land use detriments and a review and possible reassignment of coastal development and tourism activities to more suitable locations will enhance the natural resource and provide opportunity for sustainable use.
The decision to make these areas MPAs were primarily due to their "productivity," however, their productivity may have been caused by the fact that these areas were the spillover points from the less accessible and more dangerous fishing areas that surround them.
The spillover theory does have some merit, as it will work for certain species, if the location is chosen correctly and the boundaries are appropriate. However, applying the spillover theory to Guam's current marine preserve areas is far-fetched. The creation of the MPAs was not able to take into account these findings and the MPAs were put in places that the people of Guam used for fishing.
The Legislature should look at repealing or amending Public Law 21-24 so that other management tools (or proper MPAs) can be developed to protect Guam's coastal resources.
There are some problems with Bill 190, which can be fixed, but it does put the MPA discussion back on the table. Our natural resource agencies need to stop avoiding their responsibilities. We need accountability.
John S. Calvo is resident of Tamuning-Tumon.